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Refinement of bending stiffness and compression strength as measurement of wood decay in accelerated test methods.

机译：在加速测试方法中改进了木材弯曲度的抗弯刚度和抗压强度。

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摘要

The mechanical properties of wood are very sensitive to wood decay, but accuracy and reproducibility problems have limited its use in wood decay tests. To address these problems, a modified method of evaluating wood preservatives in an accelerated soil contact test was explored using small decay cups containing unsterile soil and thin (3mm) pine sticks. It was found that the decay rate was rapid, with significant decay being detectable in untreated wood after two months exposure. The extent of wood decay was measured by monitoring changes in the bending elasticity (MOE) of the test samples, which was found to be a sensitive measure of the decay rate for both CCA and CuNap treated as well as untreated wood. The rate of wood decay in both treated and untreated wood samples was accelerated when the soil was amended with wood compost. Use of amended soil also resulted in significantly higher copper depletion rates for CCA treated wood, but not for the CuNap treated wood.; It was also found that in this study that the MOE of 3mm thick southern yellow pine sticks decreased slightly after three bending cycles with a deflection of 2mm, which is under the proportional limit of the sticks. This finding is in contrast to a general understanding that MOE is not compromized when the deflection is less than the proportional limit. It was also found that sterilizing the sticks by autoclaving resulted in a decrease in MOE of approximately 10%, but no further change was observed when the sticks were repeatedly deflected for six cycles. For decayed sticks, there was only a slight decrease in MOE when they were repeatedly bent for six cycles after the decay was arrested. The proportional limit of the decayed sticks subjected to 2mm deflection was not exceeded until the decay advanced to an MOE loss about 40-50%.; Wafer distribution schemes were explored for a new soil block decay test which uses compression strength to determine the extent of wood decay. The results showed that randomized complete block distribution minimized variation.
机译：木材的机械性能对木材腐烂非常敏感，但是准确性和可重复性问题限制了其在木材腐烂测试中的使用。为了解决这些问题，探索了一种改良的方法，用于在加速土壤接触试验中评估木材防腐剂，方法是使用装有未消毒土壤和细（3毫米）松木棍的小衰减杯。发现腐烂速度很快，暴露两个月后未处理的木材可检测到明显的腐烂。木材腐烂的程度是通过监测测试样品的弯曲弹性（MOE）的变化来衡量的，这被发现是CCA和CuNap处理以及未处理的木材对腐烂率的敏感度量。当用木材堆肥改良土壤时，处理过的和未处理过的木材样品中的木材腐烂速度都加快了。使用改良的土壤还可以使CCA处理过的木材的铜消耗率显着提高，而CuNap处理过的木材则没有。还发现，在这项研究中，3毫米厚的南部黄松木棒的MOE在三个弯曲周期后略有下降，挠度为2mm，这低于木棒的比例极限。这一发现与一般理解相反，即当挠度小于比例极限时，MOE不会受到影响。还发现通过高压灭菌对棒进行灭菌导致MOE降低约10％，但是当棒重复偏转六个周期时未观察到进一步的变化。对于腐烂的棍棒，在阻止腐烂后将其反复弯曲六个周期时，MOE只会略有下降。直到衰减前进到大约40-50％的MOE损耗，才超过衰减棒的2mm偏转的比例极限。针对新的土壤块腐烂试验，探索了晶片分配方案，该试验使用抗压强度确定木材腐烂的程度。结果表明，随机完整块分布使变化最小。

著录项

  • 作者

    Li, Gan.;

  • 作者单位

    Mississippi State University.;

  • 授予单位 Mississippi State University.;
  • 学科 Agriculture Wood Technology.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 129 p.
  • 总页数 129
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 森林采运与利用;
  • 关键词

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